Using graphene oxide to enhance the bonding properties between carbon fibers and cement matrix to improve the mechanical properties of cement-based composites

The mechanical properties of carbon fiber (CF) reinforced cement-based materials are significantly influenced by the interface performance between CF and cement matrix. Improving this interfacial bond can be achieved through the electrophoretic deposition (EPD) method, using graphene oxide (GO). The efficiency and quality of GO deposition on the CF surface are directly related to the EPD parameters. Therefore, in this study, GO electrophoretic deposition CF (GO/CF) was prepared by controlling two key EPD parameters: voltage (10 V, 15 V, 20 V) and time (20 min, 40 min, 60 min). Furthermore, the reinforcing effects of the GO/CF obtained through EPD treatment was compared to those of 3-aminopropyltriethoxysilane modified CF (APS/CF) prepared by common surface treatment method (silanization). The results of single fiber pullout test indicated that GO/CF-15/60 (treated at 15 V for 60 min) had the best bonding performance with cement matrix among the silanized and various EPD-treated samples. Compared to untreated CF, the bond strength of GO/CF-15/60 to the matrix increased by 262 %, and it was also 88.5 % higher than that of APS/CF. This is because GO with wrinkled structure and oxygen-containing functional groups form the optimal deposition morphology and quantity on the CF surface under this EPD parameter. This promotes the adhesion of more hydration products to the CF surface, leading to increased densification with the surrounding matrix. In terms of mechanical properties, when the fiber content was 0.5 vol%, the flexural and compressive strengths of GO/CF-15/60 reinforced cement paste increased by 25.53 % and 5.25 % at 28 d, respectively. The improved interfacial properties facilitate better load transfer between the fiber and matrix, effectively inhibiting the propagation of surrounding microcracks and resulting in superior mechanical strength. A comparison of the bond strength of each modified fiber with the mechanical strength of the corresponding cement paste revealed a strong positive correlation. Therefore, by controlling EPD parameters, the optimal interfacial properties of CF/matrix can be achieved, significantly enhancing the mechanical properties of cement-based materials.